Across
- 3. theory that evolution occurs with relatively sudden periods of speciation followed by long periods of stability
- 4. theory that evolution occurs in small gradual steps over time
- 6. factor that prevents a hybrid zygote from developing, or prevents hybrid offspring from reproduction; operates after fertilization
- 7. heredity changes in groups of living organisms over time
- 8. theory of evolution developed by Darwin, based on four ideas; excess reproduction, variations, inheritance, and the advantages of specific traits in an environment
- 11. shift of a population toward an extreme vision of a beneficial trait
- 13. states that the allelic frequencies in populations stay the same unless they are affected by a factor that causes change
- 14. anatomically similar structure inherited from a common ancestor
- 15. Darwin's term for the selective breeding of organisms selected for certain traits in order to produce offspring having those traits
- 16. study of the distribution of plants and animals on Earth
- 17. morphological adaptation in which one species evolves to resemble another species for protection or other advantages
- 19. structure that has the same function but different construction and was not inherited from a common ancestor
- 20. change in the frequency of a trait based on competition for a mate
Down
- 1. most common factor of natural selection in which organisms with extreme expressions of a trait are removed
- 2. factor that prevents individuals from different species from mating; operates before fertilization
- 5. process in which individuals with average traits are removed, creating two populations with extreme traits
- 9. random effect that can occur when a small population settles in an area separated from the rest of the population and interbreeds, producing unique allelic variations
- 10. random change in allelic frequencies in a population
- 12. reduced form of a functional structure that indicates shared ancestry
- 18. organism's early prebirth stage of development